AP Biology Chapter Summary

Biology, the study of life and living organisms, is complex and encompasses a multitude of theories and ideas. In AP Biology, the first unit covered was evolution. Chapters 29, 31, 39, 40, 41, 42, and 43 in the textbook, Campbell’s Biology in Focus, not only discusses the four main ideas of biology: evolution, energy, information, and systems, but it also gives examples of each in order to help guide the reader’s understanding of the concepts. The first big idea of AP Biology is: “the process of evolution drives the diversity and unity of life.” Chapter 39 in the textbook encompasses this main idea through discussing natural selection and genetic diversity. Natural selection, the process in which individuals that have certain inherited

The constant movement of solutes and water across cellular membranes is an overarching concept that helps to maintain cells’ growth and dynamic homeostasis. Water potential, the measure of the relative tendency of water to move from one area to another, takes into consideration the concentration of free water molecules. It is calculated using the following formula: water potential (Ψ) = pressure potential (Ψp) + solute potential (Ψs). The water in an organism moves down a concentration gradient, from an area of high water potential to low potential. In walled cells, turgor pressure, the resistance to water movement by the cell wall, also affects osmosis. When cells are placed in a hypertonic solution, one with a higher solute concentration and lower water potential, water will move from the cell to the solution, causing the cell to be flaccid, or limp. As water diffuses out of a cell, it undergoes plasmolysis, in which the cell’s living part, including the plasma membrane shrinks and pulls away from the cell wall. On the contrary, when cells are placed in a hypotonic solution, one with a lower solute concentration and higher water potential,

These relationships include competition (negative interactions that occurs among organisms whenever two or more organisms require the same limited resource), predation (biological interactions where a predator feeds on its prey), herbivory (when animals eat plants or plant-like organisms), symbiosis (when two or more species live in direct contact with one another), and facilitation (species interactions that benefit at least one of the participants and cause harm to neither). These interactions between and within populations also influence patterns of species distribution and abundance that are discussed in chapter 40. One factor that greatly contributes to the global distribution of organisms is dispersal, the movement of individuals away from their birthplace or center of high population density to their breeding site. There are three main patterns of dispersal: clumped, uniform, and random spacing. Dispersal is key in understanding geographic isolation in evolution as well as the broad patterns of species distribution that occur in the world